The present invention relates to power modules and, more specifically, to an integrated power package for motor control utilizing internal terminals for heat dissipation.
Power modules employing semiconductor devices are used in many different applications. One popular use for power modules is for driving and controlling motors. These power modules often use field effect transistors (FETs), particularly power metal oxide FETs (MOSFETs) to supply power to drive the motor based on signals received from a low power control circuit. While FETs are capable of switching the high currents needed to drive a powerful motor such as might be found in an automotive power steering mechanism, they also generate a significant amount of thermal energy when switching these large currents.
Large heat sinks are often used to dissipate the thermal energy generated by the FETs. This leads to large module package sizes and complicated semiconductor mounting arrangements. Also, locating the sensitive low power control circuitry close to the power semiconductors can reduce the reliability of the module and effect its operation due to the damaging thermal energy radiated by the FETs.
These module packaging requirements can be particularly onerous in automotive applications where the power module must be small and be co-located with the motor being driven. For example, a power steering electric motor driver module is optimally mounted directly to the mechanical power steering components it is driving. The presence of large heat sinks or extensive wiring and cabling between the power semiconductors and the module control circuitry is undesired as it prevents an efficient use of power semiconductor devices to control an electric motor.
The present invention provides a power semiconductor module that is compact, capable of driving high torque electric motors including switched reluctance motors and has the control circuit integrated within the module. The power, ground and motor terminals extend through the shell of the module such that the high power devices are mounted directly thereto. High power devices are interconnected without the use of wires or cables.
The power module of the present invention is arranged to direct thermal energy away from the control electronics such that thermal energy generated by the high power devices is transferred to a metallic substrate base, thereby providing a reliable module which is also compact such that is can be mounted proximate to the motor it is controlling.
The present invention provides an electronic module in which there is a base and a power shell coupled to the base. The power shell has a plurality of walls forming an internal chamber and at least one conductive region. At least one electronic device is mounted to at least one conductive region. A circuit board is positioned within the internal chamber of the power shell.
The present invention further provides an insulated metal substrate plate for an electronic module, in which the plate has a thermally conductive metallic substrate. A first insulating layer is affixed to the metal substrate in which the first insulating layer substantially covers the metal substrate. At least two conductive regions are affixed to the insulating layer, the at least two conductive regions being etched to form a plurality of discrete regions. A second insulating layer is disposed between the at least two conductive regions, and a solder mask is disposed on the at least one conductive region.